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U.S. Department of Transportation U.S. Department of Transportation Icon United States Department of Transportation United States Department of Transportation

Interpretation Response #20-0088

Below is the interpretation response detail and a list of regulations sections applicable to this response.

Interpretation Response Details

Response Publish Date:

Company Name: National Presto Safety

Individual Name: J.R. Nerat

Location State: WI Country: US

View the Interpretation Document

Response text:

March 24, 2021

J.R. Nerat
Senior Technical Director
National Presto Safety
3925 North Hastings Way
Eau Claire, WI  54703

Reference No. 20-0088

Dear Mr. Nerat:

This is in response to your November 12, 2020, letter requesting clarification of the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180) applicable to the periodic cylinder requalification period for Department of Transportation (DOT) specification 3AL cylinders used as fire extinguishers.  Your questions are paraphrased and answered below.

Q1. You ask whether the requalification periods identified in Table 1 to paragraph (a) of § 180.209 are intended to establish the maximum periodic cylinder requalification intervals for DOT cylinders.

A1. The testing intervals established in Table 1 to paragraph (a) of § 180.209 are the maximum time frame allowed between testing intervals for each respective cylinder specification. However, the HMR does not prevent the requalification of cylinders in more frequent intervals than required.

Q2. You ask whether § 180.209 allows a fire extinguisher manufacturer to specify a shorter maximum 10-year periodic retest interval in lieu of the referenced longer 12-year periodic interval for DOT 3AL cylinders.

A2. As stated in A1, the requirements in § 180.209 would not prevent cylinders from being tested on a more frequent basis than what is required by the HMR. Specifically, § 180.205(c) states that "a cylinder may be requalified at any time during or before the month and year that the requalification is due."

Q3. You ask whether the HMR permits additional markings to assist fillers in properly differentiating and identifying the applicable recommended DOT periodic cylinder requalification requirements.

A3. As stated in A2, the HMR does not prevent a cylinder manufacturer from recommending shorter testing intervals for cylinders. Section 178.35(f)(6) provides that "other markings are authorized provided they are made in low stress areas other than the side wall and are not of a size and depth that will create harmful stress concentrations. Such marks may not conflict with any DOT required markings." Therefore, markings recommending shorter requalification time frames would be permitted on a cylinder provided they are in compliance with § 178.35(f)(6). Please note that a cylinder marking recommending requalification at shorter intervals than required in § 180.209 may cause confusion and PHMSA does not recommend this practice.

I hope this information is helpful. Please contact us if we can be of further assistance.


T. Glenn Foster
Chief, Regulatory Review and Reinvention Branch
Standards and Rulemaking Division

178.35(f)(6), 180.205(c), 180.209

Regulation Sections

Section Subject
178.35 General requirements for specification cylinders
180.205 General requirements for requalification of specification cylinders
180.209 Requirements for requalification of specification cylinders